1. Field of Invention
The present invention is related to an apparatus and method for preventing the entrapment of a person by the drain of a swimming pool or spa and related injury. More particularly, the invention relates to a drain apparatus for a drain located on the floor of a swimming pool or spa that is coupled to a water recirculation system driven by a pump to extract water from the pool or spa through the drain and pump it back into the pool or spa through various inlets in the wall of the pool. More particularly, the invention relates to a method and apparatus for installing a safety swimming pool drain cover in an existing swimming pool or spa. Additionally, the invention relates to a method and apparatus for installing a safety swimming pool drain cover in new construction of a swimming pool or spa.
2. Description of Prior Art
A swimming pool or simply a pool is a container filled with water intended for swimming or water-based recreation. A swimming pool can be built of various sizes and either above or in the ground. A swimming pool may be for public or private use. Private swimming pools are mostly built in private residences and used for recreation and relaxation by adults, children, and even infants. Public pools are mostly built in hotels, schools, fitness centers, and parks. Public pools are mostly used for fitness, water sports, and training by people of all ages, including elderly and young children.
Swimming pools present a significant risk of death by drowning, especially for young children and the elderly. In regions where private pools are common, drowning is typically a major cause of childhood fatalities. As a result, the design, construction, and maintenance of pools are areas that are highly regulated by federal, state, and local governments.
Swimming pools are designed to be large containers of water with a drain, inlet connections, and a water recirculation system. The water recirculation system is driven by a large water pump that extracts water from the pool through the drain. The water that is extracted from the pool is passed through a debris collection trap and a skimmer to remove large debris such as leaves and branches. The water is then pumped into a large filter to remove other contaminants. Finally the filtered water is pumped back into the swimming pool through the inlet connections that are typically located around the interior wall of the pool.
The drain in a swimming pool creates a significant suction caused by large volume of water being extracted from the pool through the drain by the pump. The suction can be strong enough to trap a person on the drain. When a person inadvertently places parts of their body in the vicinity of an active drain, a portion of their body may become entrapped by the drain. A drain that is completely blocked can develop a strong vacuum within a fraction of a second with suction pressure that may prevent a person entrapped by the drain to be able to break free, thus leading to death by drowning.
A drain in a large swimming pool is generally located at the bottom of the deepest section, may be 6 to 10 feet below the water surface. In smaller pools or spas, the drain is also positioned at the lowest point which may be only a few feet from the surface. Thus in the use of a smaller pool or spa, there is a considerably greater likelihood that the user will come into contact with the drain.
The drains in residential swimming pools are typically 5 to 8 inches in diameter. The recirculation pumps used in pools are typically 0.75 to 2 horsepower pumps that can draw a vacuum as high as 26 inches of mercury. Thus it is possible that the body of a person, when positioned in close proximity to the drain, may be drawn down upon the surface of the drain cover to completely block the drain openings thus creating a strong vacuum that can entrap and drown a person in a few seconds. The suction pressure of this magnitude can prevent young people and some adults from pulling free from the suction of a drain that is completely blocked by the body or clothing of such person. Even if the person is able to pull free, bruises or welts may result. In at least one case, a child was drowned when his abdomen inadvertently covered and blocked the drain, whereby he was entrapped at the bottom of the pool and unable to break free.
Body entrapment typically occurs when a part of a person's torso completely covers a drain. A limb entrapment refers to accidents in which a person's arm or leg is sucked into the drain of a pool. Disembowelment accidents occur where small children place their buttocks over a drain, completely covering the drain creating a seal. Injury occurs when the greatly increased suction acts to eviscerate the child when their lower intestines are sucked out of their body through their anus.
Safety organizations, such as the United States Consumer Product Safety Commission (CPSC), the National Spa and Pool Institute (NPSI), and various governments have acknowledged the need for devices that protect against swimming pool or spa drain entrapment. In fact, in 2008, the Federal Pool and Safety Act became effective and addresses this problem of body entrapment by swimming pool drains.
To address this issue of body entrapment, some of the regulations and standards that have been enacted prohibit single point suction and require at least two drains in fluid communication with one another through a common suction line. When such an arrangement is used, complete blockage of one of the drains will not result in significant pressure differential across the blocked drain as the suction is relieved by flow through the other drains. Thus, removal of a body part from the affected drain is usually possible.
Despite the prohibition of single point suction by construction standards and codes, this restriction is not in effect in all jurisdictions. Even when it is, installers are frequently unaware of the requirement or simply feel that it is not necessary based on their personal experience. Nevertheless, the prohibition of single point suction does not help pre-existing pools since adding a second drain to an in-ground pool is very difficult and very expensive.
In an alternative attempt to prevent suction related injuries in swimming pools, drains have been designed and commercialized with orifices that are geometrically oriented such that total blockage by a human body can be prevented. However, such drains can still cause injury when some of the orifices are covered by debris or other materials and the rest are covered by a human body. In addition, such drains are still susceptible to total blockages by human clothing that can still entrap a human and lead to panic and/or drowning. More importantly, however, such drains are mostly a combination of a drain cover, a drain body, and other components that require is assembly by the installer and are often broken or not properly installed during construction. Such drain covers are taught by U.S. Pat. Nos. 7,178,179; 7,089,607; 6,817,043; and 6,230,337.
In addition, protective safety devices have been developed that can be installed within the pipe of the circulation system to minimize the risk of suction entrapment injury. One such device is an electrical switch that automatically shuts off the circulation pump in the event that vacuum level within the piping reaches a dangerous level. However, if the circulation system of a pool incorporates a check valve, as it most often does, stopping the circulation pump does not always neutralize the vacuum level and free the entrapped person.
Other devices that have been developed for installation within the pipe of the circulation system are mechanically actuated to break the pump suction in the event a high suction condition is sensed due to covering or at least restricting the flow of water through the drain of a pool. Some of these devices introduce air into the inlet side of the pump in response to the sensed high suction condition, which results in loss of pump prime. Other devices provide for a conduit open to the atmosphere that is submerged a given distance below the pool water level and connected to the pump drain to introduce air if a predetermined level of suction is sensed. Many of such devices are very expensive, have many moving parts, and are solutions that can be implemented during the construction of a pool, not a retrofit solution for existing pools. Some of these devices also provide false signals triggered by partially or wholly filled pump and/or skimmer baskets.
Another solution taught by U.S. Pat. Nos. 5,265,631 and 7,213,275 provide for a mechanical fuse that is mounted in the lid of the debris collection trap. Upon the existence of the above average suction force, the lid is vented to permit inflow of any water present above the lid and thereafter ambient the air. The presence of the air within the debris collection trap will cause cessation of any suction pressure at the drain and at any connected skimmer.
Other relief valves have been developed to react to high levels of vacuum within the circulation system of a pool. These relief valves are designed to be installed within the pipe of the circulation system and in fluid communication with the pump. Such valves open by atmospheric pressure overcoming the pressure provided by a spring against a movable plug when the vacuum within the piping increases. Normally the spring holds the plug in the closed position. When the vacuum increases above a safe level the atmospheric pressure overcomes the spring and pushes the plug so as to open the valve to atmosphere.
In addition to the abovementioned devices, many other devices and relief valves have been developed and commercialized for installation within the pipe of the circulation system. The abovementioned devices can be very effective at releasing the suction developed under dangerous circumstances. Unfortunately, they have several technical problems that have limited their use. First, the valves typically need to be plumbed properly into the suction side of the pump. This makes installation difficult for the average homeowner and not conducive to retrofit installations. Second, the valves typically need to be mechanically adjusted for each particular swimming pool. Even if properly adjusted, the valves can be prone to nuisance trips. Third, there is a potential for unauthorized tampering of the devices. Fourth, the pump switch and/or safety device may not be installed properly. Fifth, when the vacuum level approaches the dangerous level, the valve can vacillate between closed and open. Some valves may even repeatedly open partially and reclose, not achieving full actuation unless desired actuation point has been exceed by a substantial margin. Basically the valves may start to activate too early and achieve full activation too late. Thus, the possibility of suction entrapment injury still remains.
Finally, the biggest problem with devices that are installed within the pipe of the recirculation system is the time delay that occurs between the actual entrapment of the person and the actuation of the device. Such time delay is determined by several variables, including the physical distance between the device within the recirculation system and the location of the drain in the pool. Upon blocking or restricting a substantial portion of the drain cover, water will cease to be sucked into the drain and pipe of the recirculation system. Instead, air will get sucked in place of water. Once the air is sucked, substantial vacuum pressure will be created at the drain cover that entraps a person. However, after the person is entrapped, the water already in the drain pipe line will continue to be sucked by the pump followed by the air. Once the air in the pipe line finally reaches the safety device, the vacuum suction will be terminated by the safety device. The time for the air to reach and trigger the safety device can be a few seconds. However, few seconds is sufficient time for the person entrapped by the drain to panic and drown or suffer injury.
Unless these and other practical problems associated with these safety devices used in swimming pools are resolved, the risk of people continuing to be injured or drown by entrapment at the drain of a swimming pool will persist and any effective safety device will fail to be realized.